Go Back   Ford Truck Enthusiasts Forums > Super Duty/Heavy Duty > Super Duty & Heavy Duty
Sign in using an external account
Register Forgot Password?


Super Duty & Heavy Duty 1999 to current Ford F250, F350, F450 and F550 Super Duty with diesel V8 and gas V8 and V10 engines SPONSORED BY:

Welcome to Ford-Trucks Forums!
Welcome to Ford-Trucks.com.

You are currently viewing our forums as a guest, which gives you limited access to view most discussions and access our other features. By joining our community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join the Ford-Trucks Forums community today!





 
Reply
 
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 01-24-2010, 03:49 PM
saleen065 saleen065 is offline
Senior User
 
Join Date: Jun 2008
Posts: 205
saleen065 is starting off with a positive reputation.
Battery light on, but alternator is charging???

OK I have 14.04 volts at the batteries with the engine running but my battery light is on. I had the alternator checked off the engine and on the engine and it tests good. Shows good batteries and good charging. Is there something internal to the alternator that would make the light come on even though the alternator is charging ok? Or is there something else that would make the light come on. This is on a 1999 F250 Superduty Powerstroke 7.3. I'd appreciate any help. I did the search function on here but am still not clear as to the problem.

George
Reply With Quote
  #2  
Old 01-24-2010, 04:40 PM
ReAX's Avatar
ReAX ReAX is offline
Post Fiend
 
Join Date: May 2006
Location: Central Florida
Posts: 10,007
ReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to behold
Power is sent from the battery to the key and then into the coil of the alternator. Then 12v is sent through the dash bulb and into the alternator. If the alternator has 12v on the coil and the bulb has 12 going into it, then both sides of the bulb have 12v + and no flow so no light. If the cluster is shorted out then voltage can come the bulb and light it, or it the coil is not energized, voltage can go through the bulb and light it.
__________________
<Table><TR><TD width=275>Too many mods to list, so click here.
Here are my tech write ups

</td><td> Look, see these two tow hooks? They look like tusks. And what kind of animal has tusks?</td></tr></table>
Reply With Quote
  #3  
Old 01-24-2010, 05:02 PM
saleen065 saleen065 is offline
Senior User
 
Join Date: Jun 2008
Posts: 205
saleen065 is starting off with a positive reputation.
The coil you are referring to is a coil within the alternator?
Reply With Quote
  #4  
Old 01-24-2010, 05:46 PM
ReAX's Avatar
ReAX ReAX is offline
Post Fiend
 
Join Date: May 2006
Location: Central Florida
Posts: 10,007
ReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to behold
Yes. There are a couple of coils inside the alternator. I'm not very up on how it works, but here's some idea. An outer coil is charged to create a magnetic field, then the armature is spun and starts pushing electrons around and creates an AC voltage(something like 30vac). That voltage is rectified in 12vdc which is what you want. Without the extra magnetic field you don't get the high voltage AC and I believe it either reduces the amperage or the DC volts depending on how power hungry the rest of the system is.
__________________
<Table><TR><TD width=275>Too many mods to list, so click here.
Here are my tech write ups

</td><td> Look, see these two tow hooks? They look like tusks. And what kind of animal has tusks?</td></tr></table>
Reply With Quote
  #5  
Old 01-24-2010, 06:03 PM
saleen065 saleen065 is offline
Senior User
 
Join Date: Jun 2008
Posts: 205
saleen065 is starting off with a positive reputation.
OK thanks, so if I have 12V on one of the small wires and do not have 12v on the other small wire with the engine running, the light is on. If 12v on both wires than I shouldn't have a light. That's how I think I understand it, right?
Reply With Quote
  #6  
Old 01-24-2010, 09:43 PM
ReAX's Avatar
ReAX ReAX is offline
Post Fiend
 
Join Date: May 2006
Location: Central Florida
Posts: 10,007
ReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to behold
I believe there are three pins in the pigtail. However if it's like the gas alternator, no wires in the middle because it's internally grounded to the alt case. So if you have 12v on both wires, then the alt isn't the cause of the light. Now I think I recall there being a low voltage drop to trigger the light, you must have atleast 5v or 7v to keep the light from coming on.
__________________
<Table><TR><TD width=275>Too many mods to list, so click here.
Here are my tech write ups

</td><td> Look, see these two tow hooks? They look like tusks. And what kind of animal has tusks?</td></tr></table>
Reply With Quote
  #7  
Old 01-24-2010, 10:24 PM
redford's Avatar
redford redford is offline
Moderator
 
Join Date: Sep 2000
Location: Hooterville WI
Posts: 15,905
redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.
I would suspect the alternator. Inside are 6 diode. The AC current produced by the alternator is run through the diodes and it becomes DC current. If 1 or more of these diodes go out you'll still get some output but not as much current. During episodes of higher electrical demand the current cannpt go up, so the voltage goes down. which is triggering your light.

Have your alternator retested. Hopefully the shop testing it will spin it up and put a load on it. If it still passes take a close look at your battery cables and battery,
__________________

2007 F-250 Super Cab Short Bed 4x4 XLT Sport Package 5.4L 3.73LS Tow Command

Stuart
Retired Master Sergeant

FTE Guidelines
Reply With Quote
  #8  
Old 01-25-2010, 06:16 PM
ReAX's Avatar
ReAX ReAX is offline
Post Fiend
 
Join Date: May 2006
Location: Central Florida
Posts: 10,007
ReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to behold
Do you have a diagram of a six diode rectifier? I've only seen 4 diode bridges.
__________________
<Table><TR><TD width=275>Too many mods to list, so click here.
Here are my tech write ups

</td><td> Look, see these two tow hooks? They look like tusks. And what kind of animal has tusks?</td></tr></table>
Reply With Quote
  #9  
Old 01-25-2010, 07:02 PM
bohiaa bohiaa is offline
Elder User
 
Join Date: Mar 2006
Location: Bellville TX. Wof Houston
Posts: 585
bohiaa is starting off with a positive reputation.
Start the truck.... while it's running pull the postive connection off the battery.

If the truck stays running. the alt. is GOOD.

if NOT replace the alt.
Reply With Quote
  #10  
Old 01-25-2010, 07:06 PM
ReAX's Avatar
ReAX ReAX is offline
Post Fiend
 
Join Date: May 2006
Location: Central Florida
Posts: 10,007
ReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to beholdReAX is a splendid one to behold
The problem with that is it can cause a voltage spike that could damage the computers. It's not terribly likely, but something to be concerned about.
__________________
<Table><TR><TD width=275>Too many mods to list, so click here.
Here are my tech write ups

</td><td> Look, see these two tow hooks? They look like tusks. And what kind of animal has tusks?</td></tr></table>
Reply With Quote
  #11  
Old 05-25-2011, 07:22 PM
belz's Avatar
belz belz is offline
Senior User
 
Join Date: Feb 2004
Posts: 110
belz is starting off with a positive reputation.
Hate to bring this back up but now I am having the same problem. Did you ever get this resolved? And if you did what was the problem? I will go out and test the alt plug right now and when I pass by the auto parts store I will have them bench the alternator.
__________________
2002 F350 CC SB 4wd, 6" lift, 37" tires
Reply With Quote
  #12  
Old 05-26-2011, 08:19 PM
Dave Tyler Dave Tyler is offline
Senior User
 
Join Date: Dec 2006
Location: Canyon Valley, Texas
Posts: 118
Dave Tyler is starting off with a positive reputation.
I too am having this problem, then after awhile the light went off. Also 1999 with 210,000. If I do replace the alternator, what is the difference between the high output vs the regular? mIs it worth the difference in price? No amp but pull travel trailer and other water trailer. Appreciate the input. Dave
__________________
1999 F250 SD, PSD, Auto, 220,000. 6637 w/Pete's Cover. Coolant Filter w/203 thermostat. New injectors & glow plugs, Stancor GPR. DP Tuner. AIH delete.
Reply With Quote
  #13  
Old 05-26-2011, 10:45 PM
redford's Avatar
redford redford is offline
Moderator
 
Join Date: Sep 2000
Location: Hooterville WI
Posts: 15,905
redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.redford has a spectacular reputation.
If the standard alternator worked OK for 210k miles, there is no need to upgrade to a higher output alternator.
__________________

2007 F-250 Super Cab Short Bed 4x4 XLT Sport Package 5.4L 3.73LS Tow Command

Stuart
Retired Master Sergeant

FTE Guidelines
Reply With Quote
  #14  
Old 05-27-2011, 12:34 PM
Dave Tyler Dave Tyler is offline
Senior User
 
Join Date: Dec 2006
Location: Canyon Valley, Texas
Posts: 118
Dave Tyler is starting off with a positive reputation.
Thank you for your response. It is folks like you that make this forum. I appreciate your responses and know others do too! Regards. Dave

Cleaned cables and all last night and light was off for about 15 miles this morning and then came back on. Hope to make it home.
__________________
1999 F250 SD, PSD, Auto, 220,000. 6637 w/Pete's Cover. Coolant Filter w/203 thermostat. New injectors & glow plugs, Stancor GPR. DP Tuner. AIH delete.

Last edited by Dave Tyler; 05-27-2011 at 12:35 PM. Reason: to correct spelling
Reply With Quote
  #15  
Old 04-27-2013, 06:12 AM
95250mac 95250mac is offline
Senior User
 
Join Date: Mar 2004
Location: New England
Posts: 119
95250mac is starting off with a positive reputation.
When I replaced my exhaust manifold I had the batt. light come on, then I cleaned up the cable that goes from the truck body to the manifold stud and the light went away.

Just the other day I checked the manifold bolts and made sure they were all tight, and now as of yesterday the batt. light is coming on again.

I have not had a chance to re-check the cable but I am going to and when I do I will let you know the outcome.
Reply With Quote
Old 04-27-2013, 06:12 AM
 
 
 
Reply

Go Back   Ford Truck Enthusiasts Forums > Super Duty/Heavy Duty > Super Duty & Heavy Duty

Tags
1997, 2002, 73, 99, alternator, battery, charging, dash, f150, f250, ford, good, light, powerstroke, truck

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Alternator Problems. Help. Shutech Super Duty & Heavy Duty 0 07-18-2014 03:32 PM
Alternator Problems. Help. Shutech Super Duty & Heavy Duty 0 07-18-2014 03:13 PM
battery light still on after new alternator mtnboy 1997 - 2003 F150 6 08-31-2008 10:54 PM
Battery not charging & no alternator light highgearonly 1987 - 1996 F150 & Larger F-Series Trucks 5 01-30-2006 07:58 AM
Battery Drain - What is the “Alternator Field” circuit? Bowins Electrical Systems/Wiring 6 08-10-2005 08:03 AM



All times are GMT -5. The time now is 09:07 AM.


Powered by vBulletin® Version 3.8.7 AC1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Advertising - Terms of Use - Privacy Statement - Jobs
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. Ford® is a registered trademark of the Ford Motor Company.

vbulletin Admin Backup